Parsing a pointer into a void

Hey sorry if this is a dumb question, my prof. quickly went over pointers and then moved on and I am currently confused.

My prof wants us to use her code here:

void getStopWords(char *ignoreWordFileName, vector<string& _vecIgnoreWords){
return;}

(I know this will return nothing currently, I need to add code to this such as opening the ignoreWordFileName file and adding every line to the vector) and I am confused how I would call this void in the main function. I have to use a command line argument to get the filename so in my case:

fileNameIgnore = argv[3];

How would I then call the void using my fileNameIgnore? Again sorry for the dumb question, I have researched some and have been unable to find information on this. Thank you.